Chelsea Clinton showed off her baby bump Thursday as she promoted her new children's book in California, just days after being pictured enjoying a Lady Gaga concert in Las Vegas.

The pregnant 38-year-old stepped out in San Diego to flog copies of She Persisted Around the World: 13 Women Who Changed History and fans shared images on social media praising the former First Daughter who announced last month she's expecting her third child.

Donning two different printed shirts as she did her rounds talking about her new release, Clinton appeared at both a book signing and a chat at the University of San Diego.

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Chelsea Clinton showed off her baby bump Thursday at public appearances in California

She was welcomed at the University of San Diego campus to celebrate her new children's book She Persisted Around the World

Clinton is expected her third child later this summer she announce January 22

Spotted: Clinton was pictured by a fan at a Lady Gaga concert in Las Vegas only days ago

The mother paired the tops that enabled her burgeoning belly to be seen with fitted jeans and black high heels.

Book illustrated by Alexandra Boiger features Marie Curie, Malala Yousafzai and J.K. Rowling

'I loved meeting all of you!' she posted after one of her events in San Diego Thursday

Clinton shared an image of the Warwick's event with audience members holding up copies. She captioned the shot: 'I loved meeting all of you!'

During the book event she answered questions from children. When asked what it was like growing up in the White House she responded: 'My parents made it as normal as possible and also ensured that I was aware of how extraordinary it was.'

Fox 5 San Diego added she said: 'When my father ran for office and the bullying sort of took on a whole other level, it was very extreme and I’m grateful that it was so extreme, because I was 11 ... I knew that there was something fundamentally wrong with adults bullying children. It just seemed very strange to me.'

She said the best advice her mother gave her was 'to take serious criticism from serious people seriously' and 'to take unserious criticism from unserious people unseriously'.

She was in San Diego today to see how the Clinton Foundation is working with local partners including to address the needs of children in the child welfare and juvenile justice system

The former First daughter was pictured laughing and smiling as she took part in a chat

They spoke about the development of a youth-led trauma informed code of conduct that will be implemented across the county

Her Foundation partners the San Diego County Health and Human Services were also present

Clinton added that her trip was an inspiring one after meeting organisations that help young people and their families

On Twitter, she thanked the San Diego Foundation for 'supporting this important work'

Clinton added that her trip was an inspiring one after meeting organisations that help young people and their families.

Child welfare and the juvenile justice systems were the topic of discussion with her Clinton Foundation partners the San Diego Foundation.

Her Foundation partners the San Diego County Health and Human Services were also present.

They spoke about the development of a youth-led trauma informed code of conduct that will be implemented across the county.

She tweeted: 'Inspired by leaders I met yesterday in San Diego working to improve health outcomes for kids, young adults & families, including at Project A.W.A.R.E. who developed the Trauma Informed Code of Conduct & at @jitfosteryouth who showed me their proven method of training peer mentors.'

Her 13 Women Who Changed History book tells stories of the likes of Viola Desmond (pictured on the currency) Sor Juana Ines de la Cruz, and Sissi Lima do Amor

Just days before her book promotion appearances she was letting her hair down in Sin City.

A fan shared a picture of her intently watching a Lady Gaga gig in the state of Nevada.

Along with turning her brood into a trio, it's also a hat trick for Clinton as far as books go when her third comes out March 6.

The new baby in expected in the coming months.

Clinton who married 41-year-old investment banker Marc Mezvinsky in 2010, tweeted January 22: 'Marc and I have loved watching Charlotte be such a wonderful big sister and we're excited to watch Aidan become a big brother! We cannot wait to meet our newest addition later this summer.'

The New York couple's daughter was born in 2014 and son was born in 2016.

In a reply to congratulations on Twitter, Clinton said her parents Hillary and Bill are thrilled.